Hello Siddharth,
If I understand your question correctly then you want a service to be accessed at a specific port and not 8443.
So first you have to open a custom port on the gateway and Load balancer
and in the policy, you have to add a compare expression that compares the port and then start the execution of the policy.
So at the beginning, you need to add compare assertion using ${request.tcp.listenPort} is equal to your custom port such as 8444 then you can add if else logic if the port is not equal to your custom port you can stop it.
Please correct me if I am wrong
Thank you